Major functional groups

Much of the background needed to understand organic reactions has now been covered, and it s time to begin a systematic description of the major functional groups. Both in this chapter on alkenes and in future chapters on other... 

Figure 22.9 The major functional groups of lipids that may participate in bioconjugate techniques include amines, carboxylates, and hydroxyls.

Many drugs have functional groups that can be metabolized by the addition of water. The major functional groups involved are esters, amides, and epoxides. Several phase II metabolites such as sulfates and glucuronides, which will be discussed in Chapter 7, can also be hydrolyzed back to the parent drug. 

The introduction of other atoms (N, O, Cl, etc.) to organic compounds gives rise to many other functional groups. The major functional groups are shown in Table 18.2. 

The basic structure of humic substances involves a backbone composed of alkyl or aromatic units crosslinked mainly by oxygen and nitrogen groups. Major functional groups attached to the backbone are carboxylic acids, phenolic hydroxyls, alcoholic hydroxyls, ketones, and quinones. The molecular structure is variable as it is dependent on the collection of DOM available in seawater to undergo the various polymerization, condensation, and oxidation reactions and reaction conditions involved in humification, as well as the ambient physicochemical reaction conditions, such as temperature and light availability. 

The major functional groups in lignin are methoxy, phenolic hydroxy, aliphatic hydroxy, and carboxy groups. During reaction with alkylene oxide, most of the functional groups of lignin, besides methoxy groups, become... 

Different functional groups found in biomolecules. This figure includes the major functional groups. Other functional groups are found in minor amounts. 

The discussion which follows is organized in the following fashion. First a common undergraduate text was used to provide a list of standard or traditional preparations for the major functional groups dealt with herein. Most of these reactions should be familiar because they are the ones learned (or not learned) in the undergraduate course in organic chemistry. Although these methods will be listed and perhaps discussed briefly, the discussion in no way serves as a review of these methods. 

The main focus of this chapter will be to introduce the most widely used and practical ways (or real ways) to introduce the major functional groups. These latter methods have practical synthetic value and are usually the first choices in real laboratory situations, but often they differ from the standard list of preparations. What is important is that these first-choice methods must be integrated into die methods previously encountered so that a wider view of how to manipulate functional groups is achieved. 

Methane and compounds whose major functional group contains only carbon-carbon single bonds are alkanes. Carbons in alkanes are referred to as methyl, primary, secondary, and tertiary, depending upon how many other alkyl groups are attached to them. Methyl carbons have no attached alkyl groups, primary carbons have one, secondary have two, and tertiary have tliree. 

Infrared spectra of compounds belonging to each of the major functional group classes are provided in the figures in this chapter. Each figure has a summary of the im-... 

Just as we can rank the polarity of the solvent (the eluotropic series) with respect to the packing, the polarity of the molecule can be ranked based upon the presence (and/or position) of the major functional groups that it contains. Table 5-4 ranks some common functional groups in a qualitative fashion. As a rule of thumb, if a molecule has more than one functional group, the one with the largest polarity will determine the polarity of the molecule relative to other molecules in the sample mixture. 

As mentioned in Sections 1.3.2.1 and 1.3.2.2, the CEC and specific surface area (both internal and external) are higher than those of clay minerals. The functional groups of soil organic matter (Table 1.5) can be deprotonated or protonated, depending on pH. It means that they have pH-dependent charges. The major functional groups can be deprotonated at pH values characteristic of soils (pH = 6-8) so that they can sorb cations. It has been estimated that the CEC of soils comes from the soil organic matter in 20%-70% (Stevenson 1982). 

Most, but not all channels can switch between open and closed states. Switching can be accomplished by a ligand binding to the channel or by changes in the surrounding electrical field. Therefore, we have the following major functional groups of ion channels ... 

Figure 9. C-NMR spectrum of the 3K-1K molecular weight size fraction of the sample from Saganashkee Slough. Major functional groups are 1) carboxyl, 2) phenolic, 3) aromatic, 4) methoxy, and 5) aliphatic.

TABLE 11. Major Functional Groups (meq/g) in Organic Soils Varying in Their Extent of Humification"... 

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